diff options
| author | Tejun Heo <tj@kernel.org> | 2014-02-13 06:58:41 -0500 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2014-02-13 06:58:41 -0500 |
| commit | cb0f1fe9ba47c202a98a9d41ad5c12c0ac7732e9 (patch) | |
| tree | 9728e6a5883ddc8136e3a240ecaa9fea8343db66 /kernel/cgroup.c | |
| parent | 89c5509b0d71d1609761bf72d33333ab206dac9f (diff) | |
cgroup: move css_set_rwsem locking outside of cgroup_task_migrate()
Instead of repeatedly locking and unlocking css_set_rwsem inside
cgroup_task_migrate(), update cgroup_attach_task() to grab it outside
of the loop and update cgroup_task_migrate() to use
put_css_set_locked().
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Diffstat (limited to 'kernel/cgroup.c')
| -rw-r--r-- | kernel/cgroup.c | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 17b10b8efbcf..704c590a81d7 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -1715,10 +1715,13 @@ int cgroup_taskset_size(struct cgroup_taskset *tset) EXPORT_SYMBOL_GPL(cgroup_taskset_size); -/* +/** * cgroup_task_migrate - move a task from one cgroup to another. + * @old_cgrp; the cgroup @tsk is being migrated from + * @tsk: the task being migrated + * @new_cset: the new css_set @tsk is being attached to * - * Must be called with cgroup_mutex and threadgroup locked. + * Must be called with cgroup_mutex, threadgroup and css_set_rwsem locked. */ static void cgroup_task_migrate(struct cgroup *old_cgrp, struct task_struct *tsk, @@ -1726,6 +1729,9 @@ static void cgroup_task_migrate(struct cgroup *old_cgrp, { struct css_set *old_cset; + lockdep_assert_held(&cgroup_mutex); + lockdep_assert_held(&css_set_rwsem); + /* * We are synchronized through threadgroup_lock() against PF_EXITING * setting such that we can't race against cgroup_exit() changing the @@ -1738,9 +1744,7 @@ static void cgroup_task_migrate(struct cgroup *old_cgrp, rcu_assign_pointer(tsk->cgroups, new_cset); task_unlock(tsk); - down_write(&css_set_rwsem); list_move(&tsk->cg_list, &new_cset->tasks); - up_write(&css_set_rwsem); /* * We just gained a reference on old_cset by taking it from the @@ -1748,7 +1752,7 @@ static void cgroup_task_migrate(struct cgroup *old_cgrp, * we're safe to drop it here; it will be freed under RCU. */ set_bit(CGRP_RELEASABLE, &old_cgrp->flags); - put_css_set(old_cset, false); + put_css_set_locked(old_cset, false); } /** @@ -1871,10 +1875,12 @@ static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk, * proceed to move all tasks to the new cgroup. There are no * failure cases after here, so this is the commit point. */ + down_write(&css_set_rwsem); for (i = 0; i < group_size; i++) { tc = flex_array_get(group, i); cgroup_task_migrate(tc->cgrp, tc->task, tc->cset); } + up_write(&css_set_rwsem); /* nothing is sensitive to fork() after this point. */ /* |